In recent years, accompanied with the miniaturization of an optical apparatus, an information apparatus, an audio apparatus or the like, a motor used in the apparatus is also required to be in a compact and thin structure. As shown in FIG. 7, a motor for coping with its miniaturization and thinner shape has been known which includes a motor case 100 in which cutout parts 101 are formed in parts of the motor case 100 along a face parallel to an axial direction to form the shape of a bottom face part 102 of the motor case 100 in an oval shape. A manufacturing method for the motor case 100 having the cutout parts 101 has been proposed in which, after a cylindrical sidewall part 103 has been formed, the cutout parts 101 are formed by cutting out two portions of the sidewall part 103 in the axial direction (see, for example, Japanese Patent Laid-Open No. 2003-47218).
However, in the motor case 100 formed as described above, the cutout part 101 is formed by cutting out a part of the sidewall part 103 of the motor case 100 with a shearing machine provided with a sharp cutting tool or the like. Therefore, burrs are formed at an edge part 104 of the cutout part 101 in the sidewall part 103 of the motor case 100. The motor case 100 is formed of a thin plate member which is made of a steel plate structured of magnetic material such as iron on which plating is performed in order to cope with the miniaturization and thinner shape of the motor. Therefore, in the case that a burr is formed at the edge part 104 of the sidewall part 103 of the motor case 100, when a stator core is assembled in an inner peripheral face 106 of the motor case, the burr formed at the edge part 104 of the sidewall part 103 of the motor case 100 is brought into contact with an outer peripheral edge of the stator core. As a result, the sidewall part 103 of the motor case 100 is displaced on the outer side in a radial direction and the shape of the motor case 100 is deformed and thus the dimensional accuracy of the motor case 100 cannot be secured.
It is conceivable that burrs formed at the edge part 104 of the sidewall part 103 of the motor case 100 are removed by barrel processing or it is conceivable that a formed direction of the burrs is changed. However, the shape of the motor case 100 may be deformed by a load due to the barrel processing or a barrel used in the barrel processing is brought into contact with other portions such as pole teeth 105 and thus, especially, the shapes or inclinations of the pole teeth 105 may be changed. Further, since another facility or production process is required, production cost for the motor case 100 increases.